posterior tooth form.ppt

sdfghnmnbvcx

1. 1
good morning

2. HISTORY OF POSTERIOR
TOOTH FORMS
PRESENTED BY
R.PRIYA DARSHINI
1
ST
YEAR MDS

3. Contents
 Introduction
Posterior tooth form
History of the development of posterior tooth form
Types of posterior tooth forms
Anatomic teeth of 33 degree or more
Modified anatomic teeth between 30 degree and 0
degree
Non anatomic or 0 degree cuspless teeth
Problems with anatomic tooth form
Problems with Nonanatomic tooth form
Evaluation of occlusal form
Comparison of different types of teeth in same denture
wearer
Reference

4. INTRODUCTION
The posterior teeth are primarily selected to satisfy
masticatory functional requirements. Both the
anterior and posterior teeth must function in
harmony with and be anatomically and
physiologically compatible with the surrounding
oral environment.
Occlusal surfaces are the primary concern in
selecting the form of posterior teeth.

5. TOOTH FORM
The characteristic of the curves, lines, angles,
and contours of various teeth that permit their
identification and differentiation. [GPT-8]
POSTERIOR TOOTH FORM
The distinguishing contours of the occlusal
surface of posterior teeth. [GPT-8]

6. HISTORY
•Earlier teeth were carved
from stone, wood, ivory, and
metal.
•Human teeth
•Little attention was given to occlusal surfaces
•No discrimination was made between upper and
lower,right or left teeth.

7. 1808 Guiseppanglelo Foniz – Developed First
Individually fired porcelain teeth
•“Terro-metalic In-corruptible” teeth.
Called as “FRENCH BEAN” due to their bean
like shapes.

8. 1817, Parisian dentist Antoine A. Plantou
- PHILADELPHIAN ARTIST
- Mineral (i.e, porcelain) teeth were first
introduced in the United States.
•These teeth were typical of the French
bean teeth of that era.
8

9. 1822, Charles Wilison Peale
- LONDON GOLDSMITH
•Denture using human and
animal teeth attached to lead
bases.
•Steel Springs were used to retain

10. 1840 Claudius Ash
“TUBE TOOTH”
•Fixed to denture base by means of a post.
•Had crude occlusal anatomy and were unglazed.
•Molars indistinguisable from premolars.
•Cusps blunted, poorly defined, and probably not
efficient.

11. •The early posterior porcelain teeth of Claudius
Ash were unglazed and crudely carved.
•1858 Ash and sons company produced a non
anatomical teeth with inverted cusps.
Robert C.Engelmeier; Early designs for the occlusal anatomy of posterior teeth part III J.prostodont2005;14,131-136

12. •Between 1870 & 1890, Ash’s teeth evolved to the
point that there were clear distinctions between
maxillary and mandibular teeth as well as right
and left sides.
•Ash teeth by 19
th
century displayed sharp ridges
and grooves transversing their occlusal surfaces.
•These modifications may have enhanced
masticatory efficiency.
12

13. 1914 Dr. Alfred Gysi – Switzerland
“TRUBYTE TEETH”
•First anatomical porcelain tooth to function
harmoniously with incisal and condylar guidance.
•Cusp angle of 33°.
•Had transverse ridges and were intended for tight
interdigitation in Angles class I occlusion.
•Marketed by ‘THE DENTISTS’ supply company.

14. 1927 Dr. Alfred Gysi
“CROSS-BITE POSTERIOR”
•As he recognized anatomic teeth would not satisfy all
ridge relationships.
•Maxillary buccal cusp eliminated, one prominent
lingual cusp occluded into lower anatomic tooth.
•“Mortar-and- Pestle”action of the occlusal scheme

15. 1922 &1927 Victor Sears
“CHANNEL TOOTH”
•maxillary occlusal surfaces consisted of deep channel
ran mesiodistally the entire length of four posterior teeth.
•Lower posteriors are approximately half the buccolingual
width of standard anatomic teeth.
•mandibular posteriors had single central ridge that ran
entire length of occlusal table

16. 1929 Hall
“INVERTED CUSP TOOTH”
•occlusal surface similar to Ash in
1858
•Flat with concentric cone
shaped depressions
•Eliminated the problems of
denture instability owing to
presence of cusps on teeth.
16
•Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

17. 1929, Myerson
“TRUE-KUSP”
•Series of transverse buccal-lingual ridges
with sluice ways between them
17

18. 1930 Avery brothers
“SCISSOR-BITE” TECHNIQUE
•Posterior occlusal surfaces locked anteroposteriorly
•Cusp angle is determined by inclination of the
condylar path
•Shear food in lateral excursions
•No movement in protrusive
excursion

19. All the cusps are of tetrahedral form with transverse
grooves therebetween having the buccal and lingual
portions in alignment and the apices of the cusps all
lying on the surfaces.
1932 Pilkington and Turner
•Slightly shallower cusp of 30° closely resembling natural
occlusal forms.
•These posteriors were intended to provide a small degree of
freedom in protrusive excursions
•Tightly interlocked in lateral excursion.

20. 1934, Nelson
“CHOPPING BLOCK” posteriors.
•Flat occlusal surfaces with numerous ridges.
•Ridges on maxillary ran mesio-distally.
•Ridges on mandibular ran transversely
•Hence an efficient shredding and cutting action.
20

21. 1935 French
•Maxillary tooth – central groove running
mesiodistally. But with shallow buccolingual
inclines to reduce lateral thrust.
•Mandibular teeth – narrow mesiodistal food table,
moved to lingual of occlusal surface and a
slopping buccal incline that was subocclusal.
•favored the stability of lower denture by placing
the axial occlusal forces lingually.

22. 1936 McGrane
“CURVED CUSP” POSTERIOR TOOTH
•Locked anteroposteriorly and free laterally in an
arc corresponding to an arbitrary radius from
each vertical rotational axis of right and left
condyle.
•Intent was to shear food in harmony with the
lateral condyle guidance of the Bennett angle.

23. 1937 Max Pleasure's scheme.
•Modified the lower posterior teeth occlusal surfaces to
reverse curve by tilting the tooth buccally.
•This did not provide for balancing contacts in either lateral
or protrusive excursions.
Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

24. •Reverse curve in premolars – for lever balance
A flat occlusal surface on 1
st
molar and
A Monson curve (lingual tilt) at 2
nd
molar for
balancing contact in lateral position.
•Reverse curve by tilting the tooth buccally is created
to direct forces of occlusion lingually to favour
stability of lower denture, while still retaining a
balancing contact in 2
nd
molar.

25. 1939, Swenson
“NON-LOCK” posteriors
•Flat teeth with sluiceways for shredding and
allowing food to clear the occlusal table.
•They also provided balancing contacts as a
modest buccal and lingual incline was provided.
25

26. 1941 S.H. Payne
“LINGUALIZED OCCLUSION CONCEPT”
•This basic concept was not entirely new; it was
introduced by Gysi 20 years earlier.
•Upper anatomic teeth, lower Nonanatomic teeth.
Occlusion in cenric relationOcclusion in laterotrusion

27. •Lingualised occlusion concept was reported on by
POUND AND MURRELL .
1973, Pound tested 2 types of occlusion on 3 patients.
•1
st
type of occlusion–acc to stuart –full organic
occlusion
•2
nd
type –lingualised occlusion
•This showed 2 of 3 patients preferred lingualised
occlusion.

28. Clough et al
•Tested lingualized occlusion and monoplane
occlusion and found
46-33% of patients over 65 yrs - lingualized
20% - had no clear choice
86.7% of patients under 65 yrs - monoplane

29. Becker et al
•Made an important distinction about the term
lingualized occlusion.
•It shouldn’t be interpreted as placement of
mandibular teeth lingual to ridge crest.
•so, ortman suggested using the term lingual cusp
contact occlusion to describe the contact of
maxillary lingual cusp with mandibular teeth.

30. 1942, John Vincent
metal inserted in resin posteriors.
•Inserts were of gold solder wire and later
stainless steel
•Circles of metal protruded from middle third of
maxillary posterior occlusal surfaces with
shallow buccal and lingual cusps protruding
beyond metal inserts.
•These teeth were set against french’s
mandibular teeth.
•As teeth wore, heaviest masticatory force was
concentrated in anteroposterior center of
denture without tipping denture.
30

31. 1946, Hardy
Metal insert called "VO" (Vitallium Occlusal).
•Incorporated a narrow zigzag of vitallium ribbon
embedded mesiodistally on the occlusal surface
which enhanced cutting efficiancy
31

32. 1951, the Myerson Tooth Corporation
first cross-linked acrylic tooth with flat occlusal
scheme called “SHEAR-CUSP” tooth
•More wear resistant.
32
•Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

33. •So, Sears and Myerson prosposed combining
porcelain and acrylic.
•That claimed – there was less horizontal
movement of the base, less soreness and
trauma to the ridges and quieter impact sound
with softer feel that denture wearers liked
•Norman – 50% less horizontal force generated
with porcelain against acrylic resin.
33

34. •Harrison after research – porcelain teeth
opposing resin teeth causes faster wear
on acrylic teeth than when acrylic
opposing acrylic teeth.
34

35. 1952, Cook
COE’S MASTICATORS
•2
nd
premolar 1
st
molar - flat stainless steel castings with
holes on the occlusal surfaces that exicted diagonally to a
port on the buccal surface.
•They occluded with flat upper porcelain teeth to push food
in to the holes & in a grinder-like fashion, break it in pieces.
•Ports would clog with fibrous food
35•Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

36. 1954, DeVan
“NEUTROCENTRIC CONCEPTS”
•Stated that flat occlusal surfaces should have -
1) Flat planes in all directions with no inclination at all
in respect to the underlying denture foundation
2) Balance was considered unnecessary &
undesirable. As resulting inclines would create
instability of dentures.
•This concept was carried out by limiting the
mesiodistal extent of the occlusal table to avoid
setting the teeth over the lower molar slope inherent
in the posterior portion of residual ridge.
36

37. 1949 & 1957 Sears –
described Monoplane Concept of
occlusion using nonanatomic teeth with a
posterior balancing ramp which was out of
occlusion when teeth were in centric occlusion.
The ramp functioned only during eccentric
movements.
37

38. 1957, Bader –
•To increase the masticatory efficiency of flat teeth
– CUTTER-BAR” scheme
•Metal cutting bar replacing the second bicuspid,
first molar, and second molar
•Occlude with opposing upper porcelain cuspless
teeth
38

39. 1961, Sosin
•Replaced maxillary 2
nd
bicuspid and 1
st
and 2
nd
molars
with cleat shaped vitallium forms called “CROSS
BLADES” of slightly smaller size.
Levin modified this scheme by reducing the size of the
cross blade to maxillary lingual cusp.

40. •Levin and sosin claim to have great increase in
masticatory efficiancy.
•This scheme is a version of functionally
generated occlusal forms as described and
advocated by Mehringer with addition of metal
inserts.

41. 1967, Frush
“LINEAR OCCLUSAL CONCEPT”
•Maxillary and mandibular posteriors were flat,
with a single mesiodistal ridge usually on the
lower.
•minimize the force of penetrating food by
sharp linear contact
41

42. MYERSON’s FLX “freedom in lateral
excursion” posteriors are purportedly
engineered to result in this end.

43. POSTERIOR TOOTH FORMS
Divided into two main groups:
•Anatomic
•Nonanatomic.

44. ANATOMIC TOOTH
•Designed to stimulate the natural tooth
form.
•Cusp height of varying degrees of
inclination that will intercuspate with
opposing tooth
•standard anatomic tooth has cusp inclines
of approximately 33°

45. SEMI-ANATOMIC TOOTH
•If cusp incline is less steep than the
conventional anatomic tooth of 33° - it is
classified as a modified or semi-anatomic
tooth.

46. NON-ANATOMIC TOOTH/ 0
DEGREE CUSPLESS TEETH
•Occlusal surface is flat
•No cusp heights to interdigitate (lntercuspate)
with an opposing tooth.
•The occlusal surface is composed of varying
designs of flat planes and sulci to enhance its
comminuting effect on food.

47. PROBLEMS WITH ANATOMIC
TOOTH FORMS
•Use of Adjustable articulator is mandatory
•Eccentric records must be made for articulator adjustments.
•Mesiodistal interlocking will not permit settling of the base
without horizontal forces developing.
•Harmonious balanced occlusion is lost when settling occurs
•Bases need prompt and frequent refitting to keep the
occlusion stable and balanced.
•Presence of Cusps generates more horizontal force during
function.
47

48. Indication
•Good general health
•Well healed ridges in an ideal relationship.
Recall the patient and examine at intervals not
to exceed six months.
•Minute loss of vertical dimension which may
occur, due to abrasion of teeth, resorption of
bone. This change rob the wearer of comfort
48
Clare W sauser,Posterior occlusion in complete denture occlusion J prosthet dent 1957,7,456

49. Contraindication
•Patient suffering from chronic systemic
illness,
•those said to negative bone factors
49
Clare W sauser,Posterior occlusion in complete denture occlusion J prosthet dent 1957,7,456

50. Advantages
•Ease in developing bilateral balanced articulation between
maxillary and mandibular teeth during eccentric movements.
•More efficient in cutting food – reducing forces directed at
support during masticatory movements.
•Resemble natural teeth and acceptable esthetically.
•Contours like natural teeth – hence compatible with oral
environment.
•An attempted occlusion without cusps is disorganised bcos
occlusion has depth; it is not a sudden closure of flat surfaces.
50

51. Disadvantages
•Possible damage to supporting tissues due to
deflective contacts of cusped teeth when vertical
dimension of occlusion is lost through resorption.
•When bone loss occurs and the denture base
moves forward, a malrelation of opposing cusps will
direct the upper denture forward and lower denture
backward, leading to discomfort and irritation of soft
tissues and potentially more bone loss
51

52. PROBLEMS WITH NON ANATOMIC
TOOTH FORMS
•occlude in only two dimensions,
•less shearing efficiency.
•Bilateral and protrusive balance is not
possible with a purely flat occlusion.
•dull and unnatural appearnce.
•tendency for ridge resorption due to cuspal
interference is minimized with flat cusp
52

53. Non-Anatomic teeth are preferred under the
following circumstances
•Abnormal closure patterns,
•Devoid of any firm ridge foundation;
•Presenc of posterior, extremely yielding
displaceable mucosa;
•Tortuous ridges combined with an
excessive denture space
53•Sumuel Friedman;A computer analysis of conflicting factors in the selection of the occlusal pattern
for edentulous patient J prosthet dent 1964 14,30-43

54. Advantages
•Versatility in class I and III jaw relationships
•Closure of jaws over a broad contact area.
•Creation of minimal horizontal pressures.
•Easier maintenance of the complete denture
occlusion
•Fabrication of dentures with simple
techniques and articulators

55. Disadvantages
•Lack of esthetic quality
•Some patients complain of inability of
penetrating food with the flat biting surface
of non-anatomical tooth.

56. EVALUATION OF OCCLUSAL FORMS
•Masticatory efficiency
•Forces directed to the ridges.
56

57. Comparison of Different Types of Teeth
in the Same Denture Wearer
•Thompson in 1937 did a study of mastication efficiency of
33° anatomic 20° modified anatomic Hall's inverted cusp
tooth and Sears' channel were tested.
•All teeth seemed to produce about the same comminuting
efficiency except sears channel teeth.
•Patient felt he could’t control food on the blade like food
table of shears
57
Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

58. Sobolick (1938)
•Trubyte 33° teeth, Trubyte 20° teeth, French's
posteriors, True-Kusp, and Hall's inverted cusp.
•showed no clear superiority for any one form
•He ranked Hall's inverted cusp, True-Kusp, and
French's, in that order, as more com
­fortable
than Trubyte 33° and 20° teeth
58
Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

59. Payne did a study comparing anatomic teeth
(trubyte 33 ) with nonanatomic teeth
•Anatomic teeth performed better
1951 Payne compared anatomic with different non-
anatomic teeth ( True –kusp, French’s, Hardy VO
posteriors.
•Initially anatomic showed better performance, but
a swalloaing threshold both were similar
59
Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

60. •Trapozzano and Lazzari compared the
masticatory efficiency of Trubyte 20 ,Halls in
­
verted cusp, and DeVan's nonanatomic posterior
teeth.
•20° teeth showed superiority over the
nonanatomic teeth.
60
Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

61. Einar Berg in 1988
•Studied on influence of cusped and cuspless
teeth on patient satisfaction with complete
denture
•Indicates that use of cusped or cuspless
posteriors is of little importance with regards
to patient satisfaction
61•Enar Bery;The influence of cusped and cusless teeth on patient satisfaction with complete
denture,A 2 year follow up stud J dent 1988,16,269,276

62. •In 2007 A.F.Sutton and J.F.McCord did a
randomized clinical trial comparing anatomic,
lingualized, and zero-degree posterior occlusal
forms for complete dentures.
•Lingualized or anatomic posterior occlusal forms
exhibited significantly higher levels of
satisfaction compared with 0-degree occlusal
forms.
62
•A.F.Sutton and J.F.McCord A randomized clinical trial comparing anatomic,
lingualized, and zero-degree posterior occlusal forms for complete dentures.J prosthet
dent2007;97;292-8

63. Selecting posterior teeth
Selection of posterior teeth is base on
•Size
•Occlusal form
•Materials
•shade
63
Zarb-bolander Prosthetic Treatment for edentulous
patients, 12
th
edition

64. Occlusal form
•Occlusal surface are primary concern
•Base on biomechanics needs of each patient.
•No one form is best for all patients.
•Payne has discussed the selection of posterior
tooth forms should meet individual requirements
and has devised a table for a guide.
64

65. •Occlusal form will be decided by the type of
occlusion to be developed.
 Teeth to be balanced in centric or eccentric
positions – Cusp Form of tooth
 Posterior teeth are to disocclude when an eccentric
jaw relation occurs – Cusp Or Monoplane
 Posterior teeth are to arranged in a plane and
balanced in centric position only - Monoplane
65

66. TYPE OF TOOTH FORM RELATED TO RESIDUAL RIDGE
Ridge type Interridge
distance
Ridge relationPosterior type
Prominent –firmClose-idealNormal Anatomic 1
Prominent –firmAverage Prognathus Anatomic 1
Average Average Orthognathous Anatomic 2 or 3
Average Close Orthognathus Anatomic 2 or 3
Average Large Normal Anatomic 2 or monoplane
Flat-firm Large Normal Monoplane
Flat-firm Excessive Prognathus Anatomic 2 or monoplane
Flat flabby Excessive Orthognathus Monoplane reverse curve
66
1.mesiodistal unlocked,slight incline modification
2.mesiodistal unlocked,moderate incline modification
3.mesiodistal unlocked.gross modification for reverse curve in premolar

67. a) A natural tooth with its alveolar support can resist the inclined plane
effect of cusps on the teeth.
B) denture base supported by well-formed ridges, has a reistance form
to reist forces due to cusp inclines.
C) as bone resorption takes place, the resistance to lateral forces
becomes less and reduced cusp inclines are indicated to keep base
stable.
D) as ridge becomes flatter, the control of lateral forces can be
controlled by occlusal surface of artificial tooth.
67
•Winkler Sheldon: Essentials of complete Denture Prosthodontics, 2
nd
edition,

68. Type of tooth Occlusal factors Stability factorsAesthetic
factors
Teeth with cusps
Balanced occlusion possible
but may require grinding to
prevent slide from RCP to
ICP. Balanced articulation
cusps are required to obtain a
truly balanced occlusion, but
technician’s skills and time are
implict, as is sound
registration technique
If no slide present,
stability is
possible. Can be
problematic with
flat lower ridges
and in implant
borne cases.
Tend to look
better as they
look natural, as
long as teeth of
appropriate
length are used
Teeth with out
cusps
Balanced occlusion possible
and they take less laboratory
time to set up. Balanced
articulation – truly balanced
articulation is not possible with
these teeth
Absence of cusps in
the upper posterior
teeth means
balanced articulation
is not possible
Have a worn
or (attrited)
appearance
Hybrid cusps Balanced occlusion
possible by some grinding.
Balanced articulation
possible if concepts such
as lingualised occlusion
are used
Presence of cusps
or even modified
cusps can facilitate
balanced
articulation, with
reduced chance of
cuspal locking
Can look
natural
68
•MC Cord and A.A.Grant.registration stage III selection of teeth BDJ 2000,88,660
FACTORS INFUENCING SELECTION OF POSTERIOR TEETH

69. Conclusion
69

70. Reference
1) Winkler Sheldon: Essentials of complete Denture
Prosthodontics, 2
nd
edition.
2) Heartwell : Syllabus of complete dentures, 4
th
edition.
3) Sharry J.J. : Complete denture Prosthodontics
4) Zarb-bolander Prosthetic Treatment for edentulous
patients, 12
th
edition.
5) Robert L.Engelmeier:The history of development of
posterior denture teeth introduction part II Artificial
tooth development in America through the nineteeth
century. J.prosthodont 2003;12;288-301
70

71. 6) Robert C.Engelmeier; Early designs for the occlusal
anatomy of posterior teeth part III.
J.prostodont 2005;14,131-136
7) M.A.Pleasure;Anatamic versus nonanatamic teeth
J.prosthet dent 1953;3;747
8) Carl O .Boucher;Complete denture prosthodontic-
The state of the art; J.prosthet dent 2004;92,309
9) Honorut villa;Design posterior teeth J
prosthet dent 1958,9,814
10) Clare W sauser,Posterior occlusion in complete
denture occlusion. J prosthet dent 1957,7,456
11) Felix A.French,The problem of building satisfactory
denture. J prosthet dent 1954,4,769
71

72. 12) Sumuel Friedman;A computer analysis of conflicting
factors in the selection of the occlusal pattern for
edentulous patient . J prosthet dent 1964 14,30-43
13) Richar L.Myerson The use of porcelain and plastic
teeth in opposing complete dentures.
J Prosthet dent 1957,7 625
14) A.F.Sutton and J.F.McCord A randomized clinical trial
comparing anatomic, lingualized, and zero-degree
posterior occlusal forms for complete dentures.
J prosthet dent2007;97;292-8
72

73. THANK YOU
73